7
JOHNSON CONTROLS
FORM 155.21-W2 (1209)
LD06828
FIG. 10 –
MULTI-UNIT SEQUENCE
MULTI‑UNIT SEQUENCE
For multiple chiller installation application, Multi-Unit
Sequence contacts are available to start and stop each
unit. The main tained closure of a device contacts across
terminals
1
and
9
will permit the unit to operate
in all the operating modes with the “
UNIT
” switch in
the “
RUN
” (
l
) position. Conversely, an opening of the
device con tacts will inhibit the unit from operating; the
OptiView™ Control Center will then display the fol‑
lowing message: “CYCLING SHUTDOWN – AUTO
RESTART” and “UNIT SHUTDOWN BY MULTI-
UNIT REMOTE
”.
CONDENSER FLOW SENSORS
The Thermal-type analog flow sensor interfaces with
the Microboard and Paddle-type digital flow sensor
interfaces with the I/O board.
For the program to read the appropriate inputs for the
flow sensor status, the actual flow sensor type used must
be entered at the keypad SALES ORDER/CONFIG
Screen using Service Access Level. Enter "ANALOG"
for Thermal-type or "DIGITAL" for paddle type.
When flow is sensed, the flow sensor contacts are closed.
Opening of the flow sensor contacts (no flow) for 30
continuous seconds causes a safety shutdown displaying
"CONDENSER - WATER FLOW SWITCH OPENED".
The flow sensor status is bypassed for the first 30 seconds
of "SYSTEM RUN".
THERMAL TYPE FLOW SENSOR
When the Thermal-type flow switch is used, the flow
switch uses the cooling effect of liquid to sense flow.
When the flow of liquid is sensed, the solid state relay
output is turned on conducting current through the mi‑
croboard load resistor to the +5VDC applying greater
than +4VDC to the microboard input J14-8.
When no flow of liquid is sensed, the solid state relay
output is turned off, this results in less than 1VDC
to the microboard input and the OptiView Control
Center will display the following message: “SAFETY
SHUTDOWN ” and “CONDENSER WATER FLOW
SWITCH OPEN”.
FIG. 11B –
PADDLE TYPE FLOW SENSOR
LD06827
PADDLE TYPE FLOW SENSOR
If desired, a condenser water flow interlock can be ap
‑
plied. Flow switch – McDonnel type FS8W, max. 150
psi (YORK Part No. 024-26116) available at additional
cost. If condenser water flow switch is not used, a jumper
must be installed between terminals 1 and 11 .
When condenser water is flowing, the flow switch con
‑
tact will close. Opening of the condenser water flow
switch contacts for 30 continuous seconds will cause
unit shutdown. The Flow Switch Status is checked 30
seconds into “System Run” and continuously thereafter.
The OptiView Control Center will display the following
message: “SAFETY SHUTDOWN” and “CONDENS
‑
ER WATER FLOW SWITCH OPEN”.
LD14443
I/O BOARD
PADDLE-TYPE FLOW SENSOR
(DIGITAL)
CONTACTS RATED
5mA @ 115VAC
or
CONDENSER WATER
PUMP INTERLOCK
MICROBOARD
THERMAL-TYPE FLOW SENSOR
(ANALOG)
FIG. 11 ‑
CONDENSER FLOW SENSORS
The OptiView Control Panel allows the use of either the
Thermal-type or Paddle-type flow sensor.